Aneurysmal Subarachnoid Hemorrhage (SAH) is one of the leading causes of morbidity and mortality associated with stroke worldwide. SAH is a neurological emergency characterized by extravasations of blood into spaces covering the central nervous system that are filled with cerebrospinal fluid. Several complications such as hydrocephalus, rebleeding, cerebral vasospasm, seizures, myocardial injury, and pulmonary edema can result from SAH.
SAH is a major concern throughout the world, with varying incidences of between about 1 and 96 incidents per 100,000 person/year (Batista da Costa Jr. et al. (2004) Arq Neuro-Psiquiatr (Sao Paulo) 62:245-249), with a worldwide incidence of about 10 per 100,000 person/year (Batista da Costa Jr. et al. (2004) Arq Neuro-Psiquiatr (Sao Paulo) 62:245-249). According to Suarez et al., SAH affects 21,000-33,000 people per year in the United States, and represents about 2-5% of all new strokes (Suarez et al. (2006) N Engl J Med 354:387-396). About 80% of cases of SAH result from rupture of an intracranial aneurysm, which itself is associated with significant risk of complications, including death. The peak age of incidence is 55-60 years, and about 20% occurs between the ages of 15 and 45 years. There is a gender difference in SAH, with a female preponderance characterized by a ratio of female to male patients ranging from 1.6-4.16:1. The incidence of SAH is also higher in African-Americans than in Caucasians.
Recent statistics indicate that about 30% of SAH patients die within the first 24 hours, and another 25-30% die within the following 4 weeks (Flett et al. (2005) AJNR Am J Neuroradiol 126:367-372). Besides the initial risks associated with SAH, a significant percentage of patients who have suffered SAH suffer from long-term cognitive impairment (Suarez et al. (2006) N Engl J Med 354:387-396), and thus SAH is associated with substantial impacts on health care resources.
While symptom management plays a major role in the treatment of SAH, there continues to be a long felt need for treatment strategies that address the underlying physiological bases for the development of secondary complications of SAH.